The present invention relates to couplings for piping, in which a male coupling connector is engaged inside a female coupling connector, the engagement causing the opening of a valve which is provided in one at least of these connectors, the valve being of rotating ball type. In a valve of such type, a closure element, of generally spherical shape, is mounted in a coupling connector with its center in coincidence with the axis of the passage channel for the fluid to be controlled. This spherical closure element, which bears against a seat at the opening of the channel in the valve chamber, has a diametrical bore which, by appropriate means, can be brought into register with the fluid passage channel of the coupling for providing the opening of the valve, or be oriented at substantially 90.degree. to the channel for providing the closing of the valve.
A valve coupling of such type is disclosed particularly in U.S. Pat. No. 4,181,149. In a typical manner, the means providing the rotation of the ball about an axis which is transverse to the axis of the fluid passage channel are constituted by a guiding slide forming an angle with the axis, provided in the spherical closure element, cooperating with a guiding stud rigidly connected to a part which, during the coupling and uncoupling operations, is subjected to a relative longitudinal displacement with respect to the part carrying the seat of the closure element and the closure element itself. An alternative suggested by U.S. Pat. No. 3,078,068 consists in rigidly connecting the axis forming the guiding studs to the spherical closure element and providing the guiding slides for the studs in the part which is subjected to the relative longitudinal displacement.
The interest of valves of such type is that they allow the provision, in the opened position, of a passage of practically constant cross-section if the bore of the closure element has the same cross-section as the fluid passage channel in the coupling connector. Moreover, the passage cross-section is important relative to diameter since, if the spherical closure element rotates through 90.degree. , the diameter of the bore can reach ##EQU1## where d is the diameter of the spherical element and e the width of the arc of the seat support surface, meaning that when e is small, there is obtained with a good approximation a diameter of the bore equal to 0.7d-0.7e. However, with a seat support surface of reduced width, it is necessary to guide the spherical element so that its rotation plane passes through the passage axis and is perpendicular to the stud axis. If this were not the case, there would be a risk that the bore or the valve cap (i.e., the portion of the spherical element providing the closing of the passage) are not coincident with the seat, which would cause leakage. In order to remedy this situation, and as is disclosed in U.S. Pat. No. 4,181,149, guiding means have to be provided, which fix the rotation axis of the spherical closure element. This leads to a complex construction, with the machining on the spherical closure element of secant faces parallel to its plane of rotation and on which are provided the axis stubs defining its axis of rotation, the support surfaces having moreover to be provided in guiding elements sliding in slides. These elements, situated laterally relative to the spherical closure element, increase the diametrical dimensions of the assembly forming the valve and therefore the diameter of the coupling. Moreover, automatism can be achieved only by using a return spring biasing the spherical closure element and the part carrying the seat against the interlocking thrust of the coupling connectors. In U.S. Pat. No. 4,181,149, this thrust is transmitted via the guiding elements of the axis stubs of the closure element or ball and in fact (due to the clearance necessary for the closure element to bear correctly against the seat), via the axis stubs, the ball and the seat. Therefore, the axis stubs are subjected to a high load per surface unit and to a corresponding wear.